For millions of Europeans, the beach is the ultimate holiday destination. That is, except when it is covered with a layer of rotting green slime, giving off lethal fumes that have killed domestic animals and caused serious poisoning in humans. So-called ‘green tides’ of algae, which disfigure some of Europe’s most beautiful beaches, are a clear indicator of nitrate pollution. This problem is often particularly severe during the summer months.

In reasonable quantities, nitrates are a vital natural fertiliser for plants. They are also a key component of industrial fertilisers and animal manure. But if nitrate levels become too high, for example in regions where intensive farming methods are used, the soil can no longer absorb them.

The film illustrates the underlying causes of nitrate pollution and the strategies that have been put in place to tackle the problem, whose origins lie in the agricultural sector. Many actions have been implemented in large part thanks to the EU’s Nitrates Directive that aims to protect water quality across Europe. The directive aims to encourage activities directed at preventing nitrates from agricultural sources polluting ground and surface waters and to promote the use of good farming practices.

When this happens, the excess nitrates end up in water courses and eventually the sea where they over-fertilise naturally occurring algae and create green tides. They can also cause other less-visible problems, for instance creating more difficult conditions for the survival of fish and aquatic insects.

The video looks at three regions affected by nitrate pollution from intensive farming:

· Brittany, in western France, which is regularly blighted by green tides - with potentially life-threatening consequences for holidaymakers and locals alike.

· The Odense Fjord in Denmark, where efforts by the authorities and local farmers have helped reduce nitrate pollution and improve water quality.

· The city of Juneda in Catalonia, Spain, where local farmers have grouped together to help finance a plant that processes pig manure to produce a dry fertiliser that can be exported outside of the region.